Mortgage on split property

robroo

I am 64 years old and I have a small mortgage 62k that is coming up for renewal. I wish to borrow an additional sum £20k to build a conservatory. My current lender will only lend up to age 75 so I have applied to my bank for a remortgage to age 80. I have private pension income into retirement and everything has been approved. 

However, when the property was valued they said it does not have an NHBC warranty. The property was a detached 1925 bungalow that was split into 2 parts in 2020 . One part(2 bed) was sold off in 2020 for £300k and since resold for £400k and we live in the other half(3 bed) . The whole of the part where we live has had no alterations and has planning, building regs, sound proofing etc. Our architect said he’s never heard of an existing build requiring a NHBC. We are very confused.They said it’s not worth anything. 
Shall I change to another mortgage company. 

Can anybody recommend one please? 

What do we do? 

MWT

Sounds like your problem is the surveyor who did the valuation and that might not change even with a different lender.

Did they actually visit or was it a desktop valuation?

Although you say the property you occupied had no alterations, presumably there must have some involved in the split?

You mentioned sound proofing etc. for example?

MWT

Sounds like your problem is the surveyor who did the valuation and that might not change even with a different lender.

Did they actually visit or was it a desktop valuation?

Although you say the property you occupied had no alterations, presumably there must have some involved in the split?

You mentioned sound proofing etc. for example?